E46Fanatics - View Single Post - Inline fuse for our amp, necessary with battery in trunk?
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Old 09-09-2012, 12:24 PM   #7
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Originally Posted by benzovs View Post
I respectfully disagree. You can wire a device up as perfect as can be, but internal components can fail, cause a short, and cause excessive current draw, which could then possibly result in a fire. When you mention military and medical devices, I conclude that you mean AC powered devices. Even though they may not have inline fuses on the device itself, the circuits that supply them power have "circuit breakers", which act as a type of fuse.
Nope, I'm talking about DC devices as well. This isn't just from guessing, but from past experience circuit breakers and fuses have a pretty high chance of failure compared to most other components, and will NOT prevent fires.

I'm not advising against fuses, but I think a lot of people put way too much trust in them. Take an amplifier like what OP is talking about and lets give the failed internal part situation like what you mentioned. If the unit has a 30 Amp fuse just to function, that means you can have a 20 Amp continuous draw and the fuse won't do anything. 20 Amps is enough to actually TIG weld thin pieces of metal together, and can easily start a fire. Also, if the person added a 30 Amp fuse but didn't crimp wires right(very common since most people don't have the right tools), you may just end up with a large cable that slips out of the inline fuse and causes a much more serious problem then likely would ever happen with an amp that had an internal failure.

With some of the stuff I deal with, and actually probably some of the competitive sound system people deal with, normal operating currents can be around 100 Amps with 200+ Amp spikes. If you use a fuse big enough not to blow during normal use, then you also have a fuse that is so big it's not going to do anything even if a wire is doing a short circuit in most situations.

In short, good practice prevents fires. Fuses and circuit breakers protect components.

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